After upgrading to WordPress 3.0.5 you will notice a bug, it is impossible to insert images in the comments, the tags img src are automatically cut out by WP core source. You will be able to see the complete code while editing a comment, but if it is published it won’t show up.

WordPress has expressed that the error will be fixed in WP 3.1. But while the new version is still not out, you can apply any of the following solutions:

Solution 3

Solution 4

This plugin provides fixes for selected WordPress bugs, so you don’t have to wait for the next WordPress core release. This does not mean you can stop updating WordPress! It just means that you’ll get a few selected fixes more quickly.